Identification of propionibacteria isolated from brown spots of Swiss hard and semi-hard cheeses

Abstract

One hundred and thirty-five propionibacteria isolated from brown spots of Appenzell, Emmental, Raclette and Sbrinz cheese were analyzed by random amplified polymorphic deoxyribonucleic acid (RAPD) and protein profiling. Both Propionibacterium freudenreichii subsp. shermanii and P. freudenreichii subsp. freudenreichii seem to be involved in the formation of brown spots in all these cheeses. In all Appenzell cheeses, in addition to P. freudenreichii, slow-growing P. acidipropionici and P. jensenii strains, which are known to cause brown spots, were found. A high proportion of unknown bacteria were noted in the brown spots of Raclette cheese. None of the isolated strains from Appenzell, Raclette and Sbrinz came from the commercial propionibacteria used in cheese production. Only one of the strains isolated was found in raw milk obtained from the same region where the cheese was produced. © Inra/Elsevier, Paris.